1. Technical Field
The disclosure relates to a liquid crystal composition and liquid crystal display employing the same, and in particular relates to a liquid crystal composition with a broad color gamut and low temperature dependence and liquid crystal display employing the same.
2. Description of the Related Art
In recent years, flexible displays (serving as electronic papers, electronic books, electronic labels, or smart cards) have been developed vigorously. The display media for flexible displays include liquid crystal displays, electronphoretic displays, electrochromic displays and electrolytic displays. In the application of electronic papers, compared with displays made of other display materials, the display made of a cholesteric liquid crystal material has higher brightness and better contrast. In addition, the cholesteric liquid crystal display can be driven passively and produced easily.
A cholesteric liquid crystal display can reflect environmental light without requiring a backlight module and a polarizer film, and therefore can provide reduced power consumption when compared with the conventional transmissive liquid crystal displays. Since the cholesteric liquid crystal display can reflect lights of various wavelengths, color images can be displayed without a color filter.
The cholesteric liquid crystal display employs a cholesteric liquid crystal composition, and a conventional cholesteric liquid crystal composition includes a nematic liquid crystal and a chiral dopant. It is desirable to use a photosensitive chiral compound having high helical twisting power (HTP) in optical writing cholesteric liquid crystal displays. The conformation of the chiral dopant in the nematic liquid crystal can be altered by illumination to result in the change of the helical twisting power (HTP), which in turn, changes the pitch (P) of the cholesteric liquid crystal to obtain a different color of reflected light.
The liquid crystal display employing the conventional cholesteric liquid crystal, however, exhibits lower reflectivity and a narrow color gamut. Particularly, when the size of the liquid crystal display is increased, a long operation time for driving is required. Therefore, a novel cholesteric liquid crystal composition for improving the color display performance and reducing the threshold voltage of the cholesteric liquid crystal display employing the same is desired.